1. Field of the Invention
The present invention relates to an acoustic imaging system for a wire guided torpedo and, more particularly, to a device mounted in the nose of a torpedo for discerning the location of a target by detecting acoustic energy emanating from the target. The invention provides means for processing target detection information and transmitting it to the launching vehicle.
2. Description of the Prior Art
In the field of target detection devices mounted on torpedoes, it has been the general practice to employ scanning techniques. Such devices scan either horizontally or vertically and detect acoustic energy from any source in the direction of scan. The energy is usually transmitted to an integrator which generates an output which is the function of the time displacement during which the energy was detected. If the source of energy is a constant source such as the screws of a target ship, the integrator indicates a continuous source of energy which can be deemed to be a target. If the source of energy is merely a transient signal, the magnitude of the output of the integrator is relatively small and the source of acoustic energy can generally be disregarded.
These systems have proved to be unsatisfactory in view of the complex equipment required for scanning. In addition, in order to enable the system to scan effectively, the integration time must necessarily be relatively small and therefore the probability of mistaking a target for a decoy or other stray acoustic energy is relatively high. In addition, such systems have displayed an inability to discern between decoying countermeasures and a true target, or between surface and bottom reflections and a true target, or the launching vehicle and the target, and at times have actually sought out the launching vehicle.
Several prior art devices have attempted to control the operation of a torpedo by a wire connected between the torpedo and the lauching station. One such device discloses a passive listening system in a torpedo that is anchored under water. The system transmits target noises back to a control station for evaluation so that the release of the torpedo may be controlled from the station. However, once the torpedo is launched, the control wire is unplugged and the launching station loses control over the torpedo.